The present invention relates to a cardiac valve prosthesis system for implantation into the body of a mammal, comprising a valve mounted on a stent element to form a stented valve element, and an anchoring element to be arranged within the aorta and spaced-apart form the stented valve element.
Valve prosthesis systems of this kind are usually used for replacing damaged, mal- or nonfunctioning cardiac valves. In the heart, cardiac valves maintain the unidirectional flow of blood by opening and closing depending on the difference in pressure on each side.
Besides the valve of the coronary sinus and the valve of the inferior vena cava, there are four valves of the heart: The two atrioventricular (AV) valves, which ensure blood flows from the atria to the ventricles, and not the other way, and the two semilunar (SL) vales, which are present in the arteries leaving the heart—i.e. on the pulmonary artery and the aorta—and which prevent blood flowing back from the arteries into the ventricles. The aortic valve, one of the semilunar valves, lies between the left ventricle and the aorta. The heart valves, except for the mitral valve, consist of three cusps or flaps which serve to seal the heart valves when closed.
The aortic valve can be affected by a range of diseases and can, therefore, require aortic valve replacement, which means that a patient's aortic valve is replaced by a different valve. The valve can either become leaky, i.e. regurgitant or insufficient, in which case the aortic valve is incompetent and blood flows passively back to the heart in the wrong direction. Further, the valve can become partially shut, i.e. stenotic, in which case the valve fails to open fully, thereby obstructing blood flow out from the heart. The two conditions frequently co-exist.
Aortic valve replacement traditionally requires median sternotomy and thus open heart surgery, which is a major impact on the patient to be treated: The chestbone is sawed in half and after opening of the pericardium, the patient is placed on a cardiopulmonary bypass machine. Once the patient is on bypass, the patient's diseased aortic valve is removed and a mechanical or tissue valve is put in its place. Besides the physical stress associated with this operation, there is a risk of death or serious complications from open heart surgery, in particular depending on the health and age of the patient.
However, recently, valves are developed that can be implanted using a catheter with out open heart surgery.
There are two basic types of artificial heart valve, mechanical valves and tissue valves. Tissue heart valves are usually made from animal tissues, either animal heart valve tissue or animal pericardial tissue, which are treated to prevent rejection and to prevent calcification. Whereas mechanical valves generally are designed to outlast the patient, they have the drawback that due to their material there is an increased risk of blood clots forming, which may only be prevented by a constant anti-coagulant therapy, which makes the patient more prone to bleeding. Mechanical heart valves are generally composed entirely of synthetic or nonbiological materials, whereas tissue (or bioprosthetic) heart valves are composed of synthetic and biological materials. Bioprosthetic cardiac valves can either represent xenografts, which are taken from different species than the recipient, or homografts, which are donor valves taken from the same species as the recipient.
EP 0 592 419 describes a cardiac vale prosthesis comprising a collapsible elastical valve which is mounted on an elastical/self-expanding stent. The commissural points of the elastical valve are mounted on the cylinder surface of the elastical/self-expanding stent, which is made from a radially collapsible and re-expandable cylindrical support element. The prosthesis is implanted in the body by means of catheterization.
Further, U.S. Pat. No. 6,652,578 discloses a prosthetic cardiac valve stent consisting of an expandable stent body member and a graft member, wherein the latter is made of biologically-derived membranes or biocompatible synthetic materials.
Nevertheless, a major disadvantage of the valves of the state of the art is their insufficient capability to be securely anchored in place of the valve to be replaced with the artificial valve. Further, many cardiac valve replacement devices do not comprise an element by means of which the artificial valve can be sufficiently secured to the place of the natural valve that is intended to be replaced. Thus, with such cardiac valves of the state of the art there is the danger of the valve migrating into the vessel and thereby not fulfilling the requirements of a replacement valve any longer.
On the other hand, in order to provide for an secure anchoring of the valve replacement device in a vessel, some of the cardiac valve replacements known in the state of the art represent stiff and bulky devices which is why such cardiac valve replacements often lead to vessel anatomy modifications and consequently to valve malfunctions.
In view of the above, an object of the present invention is to provide a new cardiac valve prosthesis system that overcomes the drawbacks of the prior art and which allows for a secure anchoring of the valve replacement device without the danger of blocking or obstructing the blood flow into adjacent vessels.